Chemical nanotechnology for transparent conducting coatings on thin-glass and plastic-foil substrates

The properties of wet-deposited transparent conducting oxide coatings (TCO) prepared by sol-gel and nanoparticle processing are presented, showing their potentials and limits for display applications. The electrical properties to a large extent are determined by their porous morphology and the resulting grain boundaries, leading to a conductivity which is a factor 10 to 50 lower compared to similar PVD and CVD coatings. Though sol-gel coatings like antimony-doped tin oxide (ATO) can be deposited at very low cost, they always require a high-temperature heat treatment limiting the choice of substrate. For a low-temperature curing of the coatings, instead, the use of crystalline conducting nanoparticles of indium tin oxide (ITO) in combination with a chemical binder offers considerable application potential. This processing not only allows the preparation of coatings with a sheet resistance of 1 to 2 k Omega/square but also a direct patterning by a fast UV curing. Typical applications for wet-deposited coatings are demonstrated including the adjustment of the properties of sputtered ITO coatings, as well as electrodes and antistatic properties on plastics substrates with a moderate conductivity in the lower k Omega/square range.